The Perfect Predators

84 Some —like the moose with its gangly legs and bul- bous nose—seem as if they might have been designed by a committee. It’s not immediately obvious how all their parts work together. So it’s all the more fascinating to see a family of animals such as the , whose every physical feature and capabil- ity seems honed for a single purpose: to hunt down and capture the small mam- mals (and sometimes ) that are their most important food. Six different species of owls are regu- larly seen or heard in Southeast , and four others visit our region occasion- ally. All these owls live by feeding on its head toward it, sometimes swiveling its head more than 180 degrees to face other animals—primarily mice, voles, and Great horned owls directly behind itself. occasionally birds. To capture these prey, are one of the owls have some remarkably powerful Owls can pinpoint where sounds are fiercest owls and senses, the most important of which are coming from because their right and left have been known hearing and sight. In fact, ornithologist ear openings differ in size and are not lo- to attack prey Paul A. Johnsgard wrote: “The heads of cated symmetrically. Owls’ heads are also many times their owls are basically little more than brains very broad, so the openings are relatively own weight. with raptorial and the largest pos- far apart. As a result, two things happen: sible eyes and ears attached.” There is a slight difference in the time it takes for a sound to reach each ear, and Ears to Hear With there is a difference in the intensity of Owls have better hearing than any the sound that reaches each ear. Together other . Many owls can locate prey these differences help owls zone in on by sound alone—when it is in tall grass, beneath the snow, or somewhere around them in total darkness. They have very “The heads of owls are large eardrums for their size, and large (Preceding page) A basically little more than boreal returns vertical ear-openings bordered with flaps brains with raptorial to its nest with a at the front side (and sometimes also the small bird it has back). The ear openings are surrounded beaks and the largest caught. by the owls’ trademark facial disks—ruffs possible eyes and ears of stiff, dark-tipped feathers that work attached.” as reflectors, channeling even very faint sounds to the ears. sounds. They may hear a mouse rustling Owls can control the movement of through the grass, or small birds twitter- both their ear flaps and the surrounding ing and jostling for space as they roost feathers, and they use them much as you together on a tree branch for the night. might cup a hand in front of your ear to concentrate sounds coming from behind you. When an owl detects a sound it turns

85 One study found, in fact, that a great gray owl can locate prey under as much as a foot and a half of snow (and in pur- suit of such prey it can break through a snow crust strong enough to support a 176-pound man). Small owls nest in natural cavities or The forward edges of the feathers holes. on an owl’s wings are serrated (unlike those of other birds, which are smooth). When owls are flying this irregularity disrupts the flow of air over their wings and eliminates the vortex noise created by air flow over a smooth surface. As a result, owls can fly more quietly than other birds. This gives them great stealth in pursuing their prey, but it may be equally important in allowing the owls to hear as they swoop or glide toward Owls do have a relatively narrow prey they can hear but not see. field of view, though (about a third of what humans have), and their eyeballs Eyes to See With do not move. But owls simply turn their Owls also have exceptionally good heads to see around them, just as they vision. Their eyes are large compared do to locate sounds. to those of many other animals. (A two- foot-long snowy owl, for example, has an Strong Talons, Camouflage, eyeball almost as large as a six-foot-tall and Patience man’s.) So owls see larger and sharper Owls have strong, sharp talons on all images than a person or many other spe- four of their toes, and they often swing cies of birds would. their outer, or fourth, toes backward. That They also have large numbers of gives the talons a two-in-front, two-in- “rods” (the photosensitive receptors in back arrangement so they have maximum the eye that allow animals to see in dim spread and maximum strength for striking light), and their pupils open widely in or carrying prey. the dark. According to some studies, One study demonstrated the tre- the eyes of certain owls have nearly six mendous strength this gives to owls as times better light-gathering power than predators. The study showed it took a human eyes have. force of more than twenty-eight and a Owls may be the only birds with half pounds to open the talons of a great true stereoscopic, or three-dimensional, horned owl. vision. This means that their prey stands Jim King, a wildlife biologist in Ju- out from its background. It is easier to neau, told us of an incident in which a see, and the owl can pinpoint its position killed a healthy captive to make an accurate strike. trumpeter that was unable to reach Owls also have telescopic vision. water to escape the owl’s attack. The owl Their eyes are located within long, bony weighed 2.6 pounds. The swan weighed sockets, so the eyeballs are elongated. 26 pounds. That gives them a long focal length, With strength owls combine stealth. much like the telescopic lens on a Besides being able to fly silently, they camera. They can focus well on distant are cryptically colored. Their mostly objects. 86 brown, gray, and black feathers blend it and warm it as if they were incubating in well with their surroundings (and the an egg. white plumage of snowy owls blends Owls such as the short-eared and well with snow). Most owls hunt by northern pygmy hunt mostly by day. remaining still, perched on branches Others such as the northern saw-whet, and watching or listening for their prey. western screech, great horned, and But even the best predators must be barred hunt mostly by night. prepared to deal with hard times. When From the perspective of a mouse or food is abundant owls may cache their vole—or even a small bird—there is no prey to be eaten later. If the prey become time of day or night when you cannot be hard frozen in winter, the owls defrost it captured by an owl. in a rather unusual manner: They sit on

Owls regularly seen in Southeast and short-eared owl. (See following pages) Alaska include: great horned owl, Owls occasionally seen in Southeast Alaska northern , western screech- include: northern hawk owl, boreal owl, owl, northern saw-whet owl, , snowy owl, and great gray owl.

What’s for Dinner?

Small mammals such as voles and mice are common prey of most owls in Southeast Alaska. We know this because after they have eaten, owls regurgitate the undigestible parts of their meal: bones, feathers, beaks, skulls, fur, and teeth. These photos show (top left) a deer mouse, (top right) a red-backed vole, and (bottom right) a pellet dropped by a short- eared owl. The pellet is surrounded by skulls and jawbones of long-tailed voles that were extracted from other pellets found in the same area.

87 Owls Regularly Found in Southeast Alaska

With Bob’s Recollections

Great Horned Owl Southeast’s most common breeding owl­—a formidable predator Length 18-25 inches

I started a lifetime would rapidly snap his fascination with owls at the age and hiss, so we knew someone of 12. I grew up close to a state was coming. I always wrapped game farm where they routinely a piece of leather around my trapped and disposed of owls forearm where Hoot perched, that preyed on the quail and but even so I can remember pheasants. I wanted to rescue the tre-mendous pressure of one nice-looking great horned his grip. owl and asked if I could have I decided to release Hoot it to raise as a pet. With my after a couple of months, which fingers crossed behind my back, was probably a good thing. I I told the workers I would never later read of several people release it. who were injured when they That’s how I got “Hoot.” He approached too close to a great would perch on my shoulder or horned owl’s nest, and of one arm and accept food from my photographer who was blinded hand. My friends and I especially while attempting to photograph liked to take Hoot along as a nesting great horned owl. a watch-owl when we went camping. He would perch near our camp, and if someone or something approached, Hoot

Northern Pygmy Owl A tiny sparrow-size owl whose plumage includes “false eyes” at the back of its neck. Length 7 inches

One spring when I was me completely, it flew back walking along the Dike Trail at to the tree and proceeded to the Juneau Airport, a northern eat the tiny brown creature pygmy owl flew out of a tree while I watched at eye level and snatched a small shrew from about two feet away. almost at my feet. Ignoring

88 Western Screech-Owl A feisty, seldom seen nocturnal hunter Length about 8-1/2 inches

One good way to determine if there are any owls in your area is to walk along at night and play a recording of the calls of different species— especially during breeding season in March and April. If an owl is within hearing distance it will usually answer. A number of years ago several of us were told that a western screech-owl had been seen along Basin Road close to the old Perseverance Mine near Juneau. In hopes of hearing or seeing it, we walked along the road one night during the spring. I carried a tape recorder over my shoulder and occasionally played the call of a western screech- owl. I got an unexpected answer. Before I knew what was happening, a screech-owl fluttered against the tape recorder, then quickly flew away. I’m not sure whether it was defending its territory or thought I was a potential mate.

Northern Saw-whet Owl A tame and retiring nocturnal hunter that feeds mostly on deer mice Length 7-1/2 inches

Some friends told me they saw a northern saw-whet owl one September when they were hunting deer at Gambier Bay. They were deep in the woods, and were startled to come upon the little owl perched on a horizontal branch only about eight feet above the ground. Unlike the Steller’s jays that had been dashing about and scolding them throughout the afternoon, the owl sat without moving, even as the two hunters walked directly beneath its perch. I have read of people being able to pick up and handle these seemingly very tame little owls during the daytime. Like other small owls, northern saw-whets nest in tree cavities. If disturbed at their nest, they usually refuse to leave the cavity.

89 Barred Owl More often heard than seen. Call is a series of distinctive and emphatic hoots that rise in intensity and sound like hoo hoo hoo hoo hoo hoo hu-HOOOOOO! Length 17-24 inches

One day in 1977 Frank its voice. We walked along Glass, a Juneau birder, sighted the trail for about three what would have been the hours periodically playing a first barred owl seen in recording of a barred owl, Alaska. It was on a trail but we got no response. bordering Peterson Creek about a mile past the end Disappointed, we of North Douglas Road returned to the car and near Juneau. To establish his decided to play the recording sighting as an official record, one last time. The owl Frank needed a photograph immediately answered us or a recording. from a tree right next to That evening at twilight the car. The recording was I joined Frank in an effort to made and Frank’s record was find the owl again and record established.

Short-eared Owl Southeast’s most easily observed owl because it hunts during the day over open country Length 15 inches

Jack Helle, a biologist with the National Marine Fisheries Service Auke Bay Laboratory near Juneau, once observed a short-eared owl snatching swimming voles from the water on the Mendenhall Wetlands in Juneau. On extreme high tides voles that live near the tideflats are often surprised by the advancing water and are forced to swim. This owl was apparently taking advantage of the voles’ dilemma. At one point Jack saw the owl dive—feet first—completely under water and emerge with a vole in its talons.

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